The correct answer is: B. Vitamin K
Vitamin K is a fat-soluble vitamin that is essential for blood clotting. It is also involved in the metabolism of bone and other tissues. Vitamin K deficiency can lead to a condition called hypoprothrombinemia, which is characterized by a prolonged bleeding time.
Vitamin C is not essential for blood clotting, but it is important for the health of blood vessels. Vitamin C deficiency can lead to a condition called scurvy, which is characterized by bleeding gums, easy bruising, and poor wound healing.
Vitamin E is not essential for blood clotting, but it is important for the health of red blood cells. Vitamin E deficiency can lead to a condition called hemolytic anemia, which is characterized by the destruction of red blood cells.
Vitamin B12 is not essential for blood clotting, but it is important for the health of nerve cells. Vitamin B12 deficiency can lead to a condition called pernicious anemia, which is characterized by fatigue, weakness, and numbness in the hands and feet.
In conclusion, vitamin K is the only vitamin that is essential for blood clotting. A deficiency of vitamin K can lead to a condition called hypoprothrombinemia, which is characterized by a prolonged bleeding time.